Development of a Process to Continuously Melt, Refine, and...

Development of a ProcessDevelopment of a Processto Continuouslyto Continuously

Melt, Refine, and CastMelt, Refine, and CastHighHigh--Quality SteelQuality Steel

Research Conducted by:Research Conducted by:University of MissouriUniversity of Missouri--Rolla and Rolla and

University of Illinois at UrbanaUniversity of Illinois at Urbana--ChampaignChampaign

Funded by US DOE DEFunded by US DOE DE--FC36FC36--03ID1427903ID14279

Development of a Process to Continuously Melt, Refine, and Cast Development of a Process to Continuously Melt, Refine, and Cast HighHigh--Quality Steel Quality Steel

Research TeamResearch TeamUniversity of MissouriUniversity of Missouri--RollaRolla

Metallurgical and Ceramic Engineering FacultyMetallurgical and Ceramic Engineering FacultyKent Peaslee, David Robertson, Jeff Smith, Von Richards, Simon Kent Peaslee, David Robertson, Jeff Smith, Von Richards, Simon Lekakh Lekakh

Metallurgical Engineering Students Metallurgical Engineering Students Jörg Peter, Darryl Webber, Aryama Jörg Peter, Darryl Webber, Aryama SaikaiSaikai, Neal Ross, Cole Eli , Neal Ross, Cole Eli

University of Illinois at UrbanaUniversity of Illinois at Urbana--Champaign Champaign Mechanical and Industrial Engineering Faculty Mechanical and Industrial Engineering Faculty

Brian Thomas, Lifeng Zhang Brian Thomas, Lifeng Zhang Graduate student (fluid flow modeling) Graduate student (fluid flow modeling)

Jun Aoki Jun Aoki

Consortium of Eight Steel Companies Consortium of Eight Steel Companies Nucor, NucorNucor, Nucor--Yamato, Yamato, GerdauGerdau Ameristeel, SMI, TXIAmeristeel, SMI, TXI--Chaparral, Bayou Chaparral, Bayou

Consortium of Three Engineering / KnowConsortium of Three Engineering / Know--how Suppliers how Suppliers CorefurnaceCorefurnace ((TechintTechint), ), ProwareProware--MetsimMetsim, , HeraeusHeraeus ElectroniteElectronite


Overview of presentation Overview of presentation

General aspects of continuous steelmaking General aspects of continuous steelmaking Examples of previous research Examples of previous research Introducing a new conceptual process Introducing a new conceptual process

Conceptual layout of process Conceptual layout of process Some information about each unit Some information about each unit

Including unit that was modeled by Lifeng Zhang Including unit that was modeled by Lifeng Zhang


Goal of ProjectGoal of ProjectConduct R & D to design a continuous steelmaking process Conduct R & D to design a continuous steelmaking process that starts with scrap and delivers high quality steel to the that starts with scrap and delivers high quality steel to the casting mold in one process. casting mold in one process.

FEATURES OF THE CONCEPTFEATURES OF THE CONCEPT =>=> POTENTIAL BENEFITSPOTENTIAL BENEFITS

Fully continuous Fully continuous =>=> High productivity, High productivity, maximum automation maximum automation

ScrapScrap--basedbased =>=> Less Refining required Less Refining required Continuous stirring of vesselsContinuous stirring of vessels =>=> Rapid mixing, high reactionRapid mixing, high reaction(Bottom (Bottom –– blowing)blowing) rates near equilibriumrates near equilibriumSeparated vesselsSeparated vessels =>=> No backflowNo backflowEnclosed processEnclosed process =>=> Safer & environmentally Safer & environmentally

friendlyfriendly


Continuous SteelmakingContinuous SteelmakingBenefits/Advantages Risks/ChallengesBenefits/Advantages Risks/Challenges

Logistics Logistics StartStart--up / Shutup / Shut--downdown

Matching to casting speed Matching to casting speed Changes or upsets to systemChanges or upsets to system

Grade changeGrade changeDelaysDelaysOffOff--specificationspecification

ConnectorsConnectorsDeslaggingDeslaggingElevation of VesselsElevation of VesselsRefractoriesRefractoriesPrevious problems Previous problems Difficult to run a pilot plantDifficult to run a pilot plantLack of real operational data

Lower capital costLower capital costSmaller vesselsSmaller vesselsLess cranesLess cranes

Higher capital utilization Higher capital utilization Less laborLess laborEasier to automateEasier to automateLess conversion timeLess conversion timeBetter energy utilizationBetter energy utilizationLess offLess off--gas (less KO61)gas (less KO61)More consistent quality More consistent quality Safer & healthier work Safer & healthier work placeplace

Enclosed processEnclosed processLess batch processing Lack of real operational data Less batch processing


Previous Research in Continuous SteelmakingPrevious Research in Continuous Steelmaking

Several processes were researchedSeveral processes were researchedTypes of vessels:Types of vessels:

CSTR CSTR -- Completely Stirred Tank ReactorCompletely Stirred Tank ReactorCounterCounter--current Reactorcurrent ReactorConCon--current Reactorcurrent ReactorEmulsion / SprayingEmulsion / Spraying

Starting material Starting material Hot metal Hot metal Scrap Scrap

Types of processes: Types of processes: Continuous operating and periodically tapping (e.g. Consteel) Continuous operating and periodically tapping (e.g. Consteel) Continuous operating and tapping into Continuous operating and tapping into ladleladleFully continuous operation (never tested)Fully continuous operation (never tested)


PFR:PFR: WORCRA cont. steelmakingWORCRA cont. steelmakingAustralia, Sweden, Australia, Sweden, Britain, USABritain, USA

1961 1961 –– 1990’s1990’sCountercurrent flowCountercurrent flowDifferent versions Different versions 10 10 tphtph Oregon ‘72Oregon ‘72

Problems/CriticsProblems/CriticsBackmixing Backmixing = = NO CONTROLNO CONTROL

Refractory wearRefractory wearHeat loss Heat loss Unsatisfactory Unsatisfactory productivityproductivity

Brooks, G.A., Ross, N.G., Worner, H.K. “Continuous Steelmaking: The Balance Between Intensity and Refining” 56th Ironmaking Conference Proceedings, Chicago, April 13 – 16, 1997, pp. 695 – 701


Emulsion CSTR:Emulsion CSTR: IRSID cont. IRSID cont. stst..FranceFrance

1963 1963 –– 1970’s 1970’s Emulsion & Emulsion & separation separation FAST KINETICSFAST KINETICS

Problems/CriticsProblems/CriticsUnknown Unknown mechanism = mechanism = NO CONTROLNO CONTROLLow iron yieldLow iron yieldLong settling Long settling times times Refractory wearRefractory wear

Berthet, A., Rouanet, J., Vayssiere, P., Trentin, B. “The IRSID continuous steelmaking process” Journal of The Iron and Steel Institute, June 1969, pp. 790 – 797


Equilibrium CSTR:Equilibrium CSTR: AISI cont. AISI cont. stst..USAUSA

1980’s 1980’s -- 1990’s 1990’s Equilibrium CSTREquilibrium CSTR

Problems/CriticsProblems/CriticsKinetic limits Kinetic limits Low iron yield Low iron yield

High initial High initial carbon and low carbon and low final carbonfinal carbonClogging of Clogging of connectors connectors transporting FeO transporting FeO

The AISE Steel Foundation “The Making, Shaping and Treating of Steel” 11th edition, Steelmaking and Refining Volume, 1998, p. 748, Fig. 13.4


UMR’s Continuous Steelmaking UMR’s Continuous Steelmaking ConceptConcept

Preheated Vessel 1 metal Vessel 2 metal Vessel 3 metal Vessel 4 steel Scrap Melter Oxidation Deoxidation Alloying to & Lime de-P(Prelim) de-C & de-P de-O & de-S Separation mold

Slag Slag Slag Slag

Baghouse To atmosphere Post- Combust Off-gas Scrap Preheat Deoxidants Alloys Electricity Fluxes Fluxes Fluxes O2 O2 Ar Ar

4 Units 4 Units -- 100% scrap based100% scrap basedMMelting Unitelting Unit

EBT AC (or DC) EAF EBT AC (or DC) EAF meltingmeltingConsteel preheating & Consteel preheating & continuous feed continuous feed Remove PRemove P

OOxidation Unitxidation UnitCSTR to remove CCSTR to remove C

RReduction Uniteduction UnitCSTR to remove O & SCSTR to remove O & SAlloyingAlloying

EEnhancement Unitnhancement UnitHomogenization Homogenization Flotation Flotation

Processing time Processing time ≅≅ 1¼ hr 1¼ hr Total liquid metal Total liquid metal ≅≅ 130 t130 t


heated holding ladle (for EAF or tundish),or pig the steel

0

1

2

3

4

5

6

7

8

9

10

11

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16length (meters)

heig

ht o

r wid

th (m

eter

s)

Ar Ar Ar

Ar

Ar

Ar

mold

CO,Ar

0.15%C

2890ºF

measure

measure

measure

measure

heating rods

Ca wire

wire feeding adjustment?

Deo

xidi

zer,

CaO

, MgO

CaO, MgO

alloys

Side view

Top viewlooking at steel surface

Conceptual layout for 110 tph process

27 t20 t20 t30 min 50 t

2910ºF 2880ºF2870ºF

2830ºF

+ 12 min + 12 min + 21 min = 75 min

melt

oxidize

reduce

homogenize & float

?

O2 + Ar

7 t –

23 t


Consteel preheater and EAFConsteel preheater and EAF

Preheat tunnel (~100 ft)Preheat tunnel (~100 ft)Continuously transports and Continuously transports and preheats scrap to ~800ºF preheats scrap to ~800ºF

NearNear--equilibrium EAFequilibrium EAFLess FeO in the slag, Less FeO in the slag, higher Fehigher Fe--yield yield

Continuously foaming slag Continuously foaming slag Electrode heats liquid Electrode heats liquid --Liquid melts scrap Liquid melts scrap

Proven technologyProven technologyhttp://www.corefurnace.com/meltshop_01.html


Preliminary Concepts Preliminary Concepts –– Melting UnitMelting UnitConsteel preheaterConsteel preheater

PostPost--combustion of CO from EAF and oxidation vessel combustion of CO from EAF and oxidation vessel More efficient = gas composition consistentMore efficient = gas composition consistent

Estimated scrap (and lime) temperature entering unit (800ºF)Estimated scrap (and lime) temperature entering unit (800ºF)

Melting similar to current EBT AC (or DC) EAFMelting similar to current EBT AC (or DC) EAF~50 tons of metal capacity~50 tons of metal capacity40 MW of power (50 MW transformer)40 MW of power (50 MW transformer)~30 minutes residence time for 110 ~30 minutes residence time for 110 tph tph

Continuous charging and tappingContinuous charging and tappingContinuous oxygen blowContinuous oxygen blow

DeDe--P and DeP and De--C (below 0.15%C) continuouslyC (below 0.15%C) continuouslyCarbon/oxygen injection for continuous foamy slagCarbon/oxygen injection for continuous foamy slagContinuous deContinuous de--slaggingslagging

Continuous Tapping Continuous Tapping


Preliminary Concept for Oxidation UnitPreliminary Concept for Oxidation Unit

CO,Ar

measure

measure

CaO, MgO

oxidize

O2 + Ar

45 scf CO / t 32 scf Ar / t

DeDe--C C Similar to Similar to continuous continuous QQ--BOPBOP

Fruehan Fruehan modelmodel

Continuous Continuous dede--slag

111 t / hr2890ºF

C = 0.15%

18 lbs flux / t

slag

30 lbs slag / t 110 t / hr2910ºF

C = 0.08%

54 scf O2 / t 32 scf Ar / tsteel weight = 20 t

time = 12 min


Fluid flow in vessel Fluid flow in vessel

“Mix”:• Homogenize composition & temperature

• Mass transport( kinetics)

• Bulk • Create interface

(turbulent energy)• Support floatation

Zhang, Lifeng “internal document” UIUC, August 2003


Preliminary Concept for Reduction UnitPreliminary Concept for Reduction Unit

or pig the steel

ArAr

Ar

measure

measureheating rods

Ca wire

?

Deo

xidi

zer,

CaO

, MgO

CaO, MgO

alloysreduce

12.4 lbs slag / t

9.4 lbs SiMn / t5.2 lbs FeSi / t(other alloys)110 t / hr

2910ºFO = 550 ppmS = 300 ppm

110 t / hr2880ºF

O = 6 ppmS = 35 ppm

~1 kWhr / t

2.2 lbs Al / t8.4 lbs flux / t

steel = 20 t t = 12 min

64 scf Ar / t

DeDe--O & DeO & De--S S Continuous Continuous dede--slagslagAlloyingAlloying

Bulk (small Bulk (small pieces) pieces)

Temperature Temperature controlcontrol

Resistant Resistant heating heating Avoid cooling Avoid cooling

Calcium Calcium treatmenttreatment

64 scf Ar / t 3.4 lbs CaSil / t


Preliminary Concept for Final UnitPreliminary Concept for Final Unit

11 12 13 14 15 16

Ar Ar Ar

Ar

mold

measure

ting rods

wire feeding adjustment

homogenize & float

110 t / hr2880ºF

32 scf Ar / t

32 scf Ar / t

small alloy additions

Final AlloyingFinal AlloyingWire injection Wire injection adjustmentsadjustments

HomogenizationHomogenizationInclusion Inclusion floatationfloatationMinimize Minimize reoxidation reoxidation Continuous Continuous transfer to mold

2.2 lbs flux / t

2.4 lbs slag / t

transfer to mold

steel weight = 34 - 50 t time = 20 - 30 min

1 – 3 strands110 t / hr2830ºF


Continuous Monitoring Continuous Monitoring

Con®Con®CeptCept: Temperature & Chemistry: Temperature & ChemistryLaser Laser –– lens lens –– spectrometer (LMF & EAF, etc.)spectrometer (LMF & EAF, etc.)

Inclusion sensor* Inclusion sensor* Size & NumberSize & Number

Temperature Chemistry

Pillwax et al. “VAI-ConCept – A Performance Package for AOD converters” AISE Steel Technology, Vol. 80, No. 9, Sept 03, p. 93

Ramaseder et al. “Continuous chemical analysis of liquid steel” Steel Times International, Nov 02, p. 30*International Report “SMK, Heraeus Develop Sensor” Iron & Steelmaker, Vol 30, No 11, Nov. 2003, p. 4


SummarySummary

Continuous steelmaking has the potential Continuous steelmaking has the potential to increase profits to increase profits Extensive previous research existsExtensive previous research existsNew conceptual process is scrap based New conceptual process is scrap based and fully continuousand fully continuousFluid flow modeling is crucial during the Fluid flow modeling is crucial during the design of the vessels design of the vessels

Development of a Process to Continuously Melt, Refine, and...

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